The present invention relates to empty-load device and more specifically, to an empty-load device with a brake cylinder test port and the brake system in which is incorporated.
An empty-load changeover apparatus is a device which senses the load of the car to which it is connected and modifies the braking signal received from a control valve to the brake cylinder. One example is shown in U.S. Pat. No. 4,884,544 to Rojecki as well as an improved version in U.S. Pat. No. 5,211,450 to Gayfer et al. These typical devices have an inlet to receive the brake signal from the control valve and an outlet to be connected to the brake cylinder. An additional port is provided for an equalization reservoir.
There are many situations where it is desirable to measure the brake cylinder pressure. This generally requires special taps put in the line prior to the brake cylinder. If it is placed at the exit of the braking signal from the control valve, it would not take into account those systems which have an empty-load device. If it is between the empty-load device and the control valve, it would not provide an accurate measurement of the brake cylinder pressure. More recently, test ports have been added to the manifold of the control valve. Again, this would be upstream of the empty-load device and not provide an accurate indication of the brake cylinder pressure downstream from the empty-load device.
The present invention provides an empty-load device with an additional brake cylinder test port which is at the same pressure as the brake cylinder port of the empty-load device. The empty-load device includes a housing having a brake cylinder, a control valve and brake cylinder test ports. A valve structure in the housing limits fluid pressure at the brake cylinder port and brake cylinder test port from the control valve port in response to a load force on the rail car. The valve structure includes a valving element and a valve seat. The brake cylinder port and the brake cylinder test port are on one side of the valve seat and the control valve port is on an opposite side of the valve seat. A check valve is provided in the brake cylinder test port which is opened when a connector is mated with a brake cylinder test port. The brake cylinder test port may be provided on the housing itself or on the pipe bracket which includes the brake cylinder port and the control valve port. An equalization reservoir port is also provided on the pipe bracket.
A railroad system which incorporates the empty-load device just described includes a control valve having an outlet providing a brake signal. The outlet of the brake control valve is connected to an inlet, which is the control valve port of the empty-load device. The brake cylinder port is an outlet and the brake cylinder test port is a test port. A valve structure limits the fluid at the device outlet and test port from the device inlet in response to a load force on the rail car. A brake cylinder is connected to the device outlet.